Method and system for detecting explosives

Abstract

A method of detecting explosives in a vehicle includes providing a first rack on one side of the vehicle, the rack including a neutron generator and a plurality of gamma ray detectors; providing a second rack on another side of the vehicle, the second rack including a neutron generator and a plurality of gamma ray detectors; providing a control system, remote from the first and second racks, coupled to the neutron generators and gamma ray detectors; using the control system, causing the neutron generators to generate neutrons; and performing gamma ray spectroscopy on spectra read by the gamma ray detectors to look for a signature indicative of presence of an explosive. Various apparatus and other methods are also provided.

1. A method of determining whether explosives are present in a vehicle, the method comprising:
 providing a neutron generator and a plurality of NaI detectors, and defining groups, the groups containing different combinations of the detectors; 
 directing energy at the vehicle using a neutron generator; 
 reading spectra from the plurality of detectors arranged around the vehicle; 
 calibrating the spectra; 
 gain shifting the spectra to a common calibration; 
 summing the spectra for respective groups; and 
 performing nitrogen detection analysis on each summed group. 
 
   
   
     2. A method in accordance with  claim 1  wherein the nitrogen detection analysis comprises identifying a nitrogen region defined by multiple overlapping peaks. 
   
   
     3. A method in accordance with  claim 1  and further comprising displaying a go/no-go message in response to the nitrogen detection analysis. 
   
   
     4. A method in accordance with  claim 1  wherein the groups are overlapping groups, with each detector being included in multiple different groups. 
   
   
     5. A method in accordance with  claim 1  and further comprising determining whether a minimum number of groups are above the nitrogen detection threshold. 
   
   
     6. A method in accordance with  claim 1  and further comprising determining whether a minimum number of groups are above the nitrogen detection threshold and, if so, providing an output indicating that the vehicle is carrying suspect cargo. 
   
   
     7. A system for determining whether explosives are present in a vehicle, the system comprising:
 a neutron generator configured to direct energy at the vehicle; 
 a plurality of NaI detectors, a plurality of groups being defined containing different combinations of the detectors; and 
 a control system configured to:
 read spectra from the plurality of detectors arranged around the vehicle; 
 calibrate the spectra; 
 gain shift the spectra to a common calibration; 
 sum the spectra for respective groups; and 
 perform nitrogen detection analysis on each summed group. 
 
 
   
   
     8. A system in accordance with  claim 7  wherein the nitrogen detection analysis comprises identifying a nitrogen region defined by multiple overlapping peaks. 
   
   
     9. A system in accordance with  claim 7  wherein the control system is further configured to provide a signal configured to indicate whether or not explosives are present, in response to the nitrogen detection analysis. 
   
   
     10. A system in accordance with  claim 7  wherein the groups are overlapping groups, with each detector being included in multiple different groups. 
   
   
     11. A system in accordance with  claim 7  and further comprising determining whether a minimum number of groups are above the nitrogen detection threshold. 
   
   
     12. A system in accordance with  claim 7  and further comprising determining whether a minimum number of groups are above the nitrogen detection threshold and, if so, providing an output indicating that the vehicle is carrying suspect cargo.